The present invention relates to a magnetic bubble memory device (hereinafter referred to as "bubble memory") and, more particularly, to the structure of a package provided with a bias field compensator for compensating the bias field in relation to temperature to ensure stable operation under a wide temperature range.
A bubble memory functions as a solid file memory having no moving parts. Recently, as the scope of use of a bubble memory has increased, its high reliability in operation and resistance against vibration and shock has attracted attention to the possible use of this device as a memory device in aircraft. In a memory device used for this purpose, when an aircraft is flying at stratospheric heights, the memory device is subjected to temperatures as low as -55.degree. C., for example, and it must carry out stable operations at such low temperatures. However, stable operation of a conventional bubble memory cannot be ensured at such low temperatures, as described hereinafter. Accordingly, it is necessary to take measures such that the device is entirely accommodated in an isothermal box so that the temperature in the space surrounding the bubble memory cannot fall to 0.degree. C. or below.